SYRACUSE, N.Y. — Penn Traffic Co. here said it has expanded its service contract with C&S Wholesale Grocers, Keene, N.H., to encompass grocery, bakery, deli, seafood, dairy, floral, frozen foods, ice cream, candy and store supplies. The new contract takes effect next month. Penn Traffic has contracted with C&S since March 2007 for distribution and warehousing services for general merchandise and health and beauty products, and it has been buying produce from C&S since last March.